1. Field of the Invention
The present invention relates to a method for combining a digital video signal and three digital narrow band signals to form a 139,264 kbit/s signal and vice-versa and it also relates to a multiplex apparatus and to a demultiplex apparatus in which a first plesiochronic digital signal having a bit rate of 135,000 kbit/s, a second plesiochronic digital signal having a bit rate of 1024 kbit/s, a third plesiochronic digital signal having a bit rate of 2048 kbit/s and a fourth plesiochronic signal having a bit rate of 64 kbit/s are combined to form a fifth digital signal having a bit rate of 139,264 kbit/s in a basic frame comprising a length of 2928 bits beginning with a 12-bit frame recognition word and a 4-bit message word, and demultiplexing first through fourth digital signals from the fifth signal, in particular utilizing a stuffing process.
2. Description of the Prior Art
The German published application No. 32 30 943 A1, fully incorporated herein, discloses a system for digital transmission of video or picture telephone signals which operate with a bit rate of 139,264 kbit/s, wherein the analog video signal is coded onto a bit rate of 135,000 kbit/s and is transmitted by way of synchronous multiplexers and synchronous demultiplexers together with narrow band signals on the basis of a 64 kbit/s raster. A synchronous network must be installed for this purpose.
An earlier proposal, namely German application No. P 34 45 355.5, relates to a combination of corresponding, plesiochronic signals to form a 139,264 kbit/s digital signal. In this method, a 1024 kbit/s signal and a 2048 kbit/s signal are combined in the first multiplexer and the intermediate multiplexed signal formed in this manner is combined with a 135015.625 kbit/s signal in a second multiplexer and is multiplexed with a signal having a bit rate smaller than 237 kbit/s. The pulse frame for the intermediate multiplex signal comprises a length of 3320 bits; the pulse frame for the 139,264 kbit/s signal is subdivided into four sections.
The positive stuffing method serving the purpose of combining plesiochronic digital signals is disclosed in the periodical "telcom report", Vol. 3, No. 4, 1980, pp. 344-352. The bit rate of 139,264 kbit/s and an appertaining pulse frame derive from the CCITT recommendation G. 751 from the "CCITT Yellow Book", Vol III, Fascicle III.3, "Digital Networks-Transmission Systems and Multiplexing Equipment", Geneva, 1981, p. 147.